Field of the Invention
The present disclosure relates to an image forming method, an image forming apparatus, and a laminated cured product.
Description of the Related Art
When forming cured films of active-energy-ray-curable inks by active energy ray irradiation, there is a method of discharging liquid droplets of the active-energy-ray-curable inks onto bases from ink discharging heads and forming images.
Various materials are suitable as the bases, including paper, metals, plastic, and glass. In terms of elongability and workability, plastic bases are preferable.
Examples of the method for forming images having a high density and clear colors on the plastic bases include a method of making cured films to be formed on the bases thick, and a method of forming cured films of white inks on the bases and forming cured films of color inks on the white ink films.
However, when a high-density image that realizes clear colors with a cured film made thick on the plastic base is to be used in an elongated form, the cured film becomes thinner as the cured film is elongated more because the elongated cured film deforms without volume change. This lowers the density and spoils the clear colors.
Hence, in order to realize a high density even after elongation, there is a need for forming a cured film on the base before elongated in a manner that the cured film has a large thickness, so the cured film may be kept thick even after elongated. However, as plotted in FIG. 1, a thicker cured film has a poorer elongability.
Accordingly, there is a problem that elongability and density or elongability and hardness are in a trade-off relationship.
In order to overcome this problem, there is proposed a printing method (see, e.g., Japanese Unexamined Patent Application Publication No. 2007-210169) including: a step of discharging an ink curable by light irradiation onto a recording medium from an inkjet head to form an ink layer in which adjacent portions of dots overlap; and a step of curing the ink layer, wherein the step of forming the ink layer on the recording medium includes at least first discharging of forming a first dot pattern, light irradiation to the first dot pattern, and second discharging of forming a second dot pattern, wherein the first dot pattern is an aggregate of ink dots arranged at intervals, and wherein the second dot pattern occupies at least part of the intervals in the first dot pattern.
There is also proposed a printing method (see, e.g., Japanese Unexamined Patent Application Publication No. 2013-022932) of delivering a first ink containing a first polymerization initiator and a first polymerizable compound and a second ink containing a second polymerization initiator and a second polymerizable compound onto a print medium in the form of liquid droplets and then curing the liquid droplets to apply printing on the print medium, wherein the first ink has a characteristic that a film obtained by curing the first ink to have a thickness of 5 μm elongates by 70 percent or greater when elongated in an environment of 150 degrees C., wherein the second ink has a characteristic that a glass transition temperature of a cured product obtained by curing the second ink is higher than a glass transition temperature of a cured product obtained by curing the first ink, and wherein delivering the first ink and the second ink onto the print medium is performed by delivering the liquid droplets of the first ink and the second ink in a manner that a first dot formed by a liquid droplet of the first ink landing on the print medium contacts a plurality of second dots formed by a plurality of liquid droplets of the second ink landing on the print medium, but adjacent ones of the second dots are spaced from each other.